Extension-ladder lock



No. 626,264. Patnted June a, less. E. C. BISHOP. EXTENSION LA'DDER LOCK.

(Application filed Apr. 7, 1894.)

(NO Model.)

N'rn STATES EDWVIN C. BISHOP, OF HARTFORD, CONNECTICUT.

EXTENSION-LADDER LOCK.

SPECIFICATION forming part of Letters Patent No. 626,264, dated June 6, 1899.

Application filed April 7,1894. Serial No. 506,665. (No model.)

To all whom it may concern.-

Be it known that I, EDWIN C. BISHOP, a citizen of the United States, and a resident of Hartford, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Extension-Ladder Locks, of which the following is a full, clear, and exact description, whereby any one skilled in the art can make and use the same.

The object of my invention is to provide an improved lock by means of which the extensible sections of a ladder may be held in place and readily operated in clamping and unclamping the ladder parts or sections by a sliding movement of one section on the other.

To this end my invention consists in the details of the several parts making up the ladder-lock and in the combination of such parts with a case and rung, as more particularly hereinafter described, and pointed out in the claims.

Referring to the drawings, Figure 1 is a detail front or plan view of parts of two adjacent ladder-sections, showing the operation of the lock. Fig. 2 is a detail view in cross-section through a side of the ladder and the lockcase, showing the connected parts. Fig. 3 is a View of the interior of the lock-case, on an enlarged scale, illustrating the position of the look when holding a part extended, the dotted outline showing the position of the parts when the section is moved up to unlock the device. Fig. at is a view of the inside of thelock-case, showing the position of the look when a section is being drawn back, the tumbler retreating into the socket in the case to allow the rung to be slid past it.

In the accompanyingdrawings, the letters a and 1) denote sections of a ladder, the former being narrower than the latter and its side parts adapted to move inside the side parts of the wider section. Preferably on the lower end of the smaller section a is secured the ladder-lock c. This ladder-lock includes a case (I, made preferably of metal cast to shape and secured to the side parts of the ladder, as by means of bolts d, which pass through the case and the ladder side and are preferably secured, as by means of nuts. The casing has a socket d 011 the inner side threaded to receive the threaded end of a rung c. There aretwo of the locks arranged opposite each other on the inner sides of the side parts a a of the section a of the ladder, and the sockets (Z are preferably provided with right and left hand threads, the rung 6 being preferably correspondingly threaded, so that it may be secured in place in the sockets in the cases. Within the case cl is a tumbler f, pivoted on a stout pivot g and having a bifurcated end, one arm f being shorter than the arm f with a rungsocket f formed at the root of the fork and between the two arms thereof. These arms are curved toward each other, so as to enable the tumbler to move easily over the surface of a rung in the operation of the device. The case is preferably closed on three sides and open on the edge which faces the rungs of the corresponding section of the ladder, and a spring h normally thrusts against the tumbler, so as to hold it in the position indicated in full lines in Fig. 3 of the drawings. When in this position, if the ladder-section is slid outward along the lower section the tumbler retreats into the position indicated in dotted outlines until the end of the arm f has passed the rung, when the tumbler then is thrust outward by the spring h, so as tohold the rung in the grasp of the tumbler, as shown in full lines. The weight of the upper section a tends to hold the tumbler firmly engaged with the rung, and thus prevents any return sliding movement of the extensible section on the main section.

In order to disengage the lock, the section carrying the lock is slid outward or upward until the rung passes the end of the arm f of the tumbler. Under the impulse of the spring h the tumbler is then thrown outward from the position with reference to the rung illustrated by the dotted outline in the lower part of Fig. 3. By a return movement of the sliding ladder-section the tumbler turns on its pivot g and retreats into the socket in the casing, compressing the spring 2' at the same time. A continued inward sliding movement ofthe section a carries the tumbler past the successive rungs on the other ladder-section .until the two sections are arranged in the desired position. To reengage the tumbler with the rung. of the main section, it is merely necessary to reverse the movement of the sliding section, and, thrusting it outward, the tumbler is again by contact with a rung turned into the position indicated in full lines in Fig. 3 of the drawings.

In place of the springs a counterpoiseweight may be provided on the inner end of, the tumbler and the latter caused to normally assume a position which will hold it extended at about right angles to the side of the casing and of the ladder side, so that it may be moved in either of the desired positions to disengage a rung or to engage a rung, as the: case may be.

In the within drawings the springs are shown as made of wire, the coiled portion resting on pins h i, one end extending outward to engage the hook and the other extending inward and lying against the side wall of the casing. Other forms of spring may be employed to control the position of: the tumbler without departing from the in-? vention, and I do not limit myself to the spe-; cial form of spring herein shown. Q

The socket d in the case is preferably re-g inforced by a web cast integral with the outer wall or cover of the case, and the web is pref erably arranged in the direction of the length of the casing to give strength in the proper position.

I claim as my invention- 1. In an extension-ladder, in combination,

lock-eases secured to an extensible ladder-section, a tumbler located in each case and adapted to support the ladder-section, inwardlyprojecting facing run g-sockets located on the lock-cases, and a rung in engagement with said sockets to prevent separation of the side parts of the ladder-section. 2. In an extension-ladder, in combination, an extensible ladder-section located between the side parts of the opposite section, lockcases secured to the inner surfaces of the side parts of the extensible section, tumblers lo= cated in said cases and adapted to support the extensible section, inwardly-projecting facing rung-sockets located in the lock-cases, and a rung in engagement with the said sockets to prevent separation of the side parts of the extensible ladder-section.

EDWVIN O. BISHOP.

Witnesses CHAS. L. BURDETT, ARTHUR B. JENKINS. 

